JP6176049B2 - Tandem quadrupole mass spectrometer - Google Patents

Description

  The present invention relates to a tandem quadrupole mass spectrometer (also called a triple quadrupole mass spectrometer), and more specifically, control parameters such as optimum voltage in multiple reaction monitoring (MRM) measurement. The present invention relates to a tandem quadrupole mass spectrometer having a function of automatically determining.

  A technique called MS / MS analysis (tandem analysis) is widely used as one technique for mass spectrometry in order to identify a substance having a large molecular weight, perform structural analysis, or quantification. There are various types of mass spectrometers for performing MS / MS analysis. The tandem quadrupole mass spectrometer is relatively simple in structure and easy to operate and handle.

  As described in Patent Document 1 and the like, in a general tandem quadrupole mass spectrometer, ions derived from a compound generated in an ion source are preliminarily described as a quadrupole mass filter (usually described as Q1). Ions having a specific mass-to-charge ratio m / z are selected as precursor ions. This precursor ion is introduced into a collision cell in which a quadrupole type (or higher multipole type) ion guide (usually described as q2) is incorporated. A collision-induced dissociation (CID) gas such as argon is supplied into the collision cell, and the precursor ions collide with the CID gas and cleave in the collision cell to generate various product ions. The product ions are introduced into a subsequent quadrupole mass filter (usually described as Q3), and product ions having a specific mass-to-charge ratio m / z are sorted and reach the detector for detection.

  One mode of MS / MS measurement in a tandem quadrupole mass spectrometer is an MRM measurement mode. In the MRM measurement mode, the mass-to-charge ratio of ions that can pass through the front quadrupole mass filter and the rear quadrupole mass filter is fixed, and the intensity (quantity) of a specific product ion with respect to a specific precursor ion is measured. . In such MRM measurement, ions and neutral particles derived from non-measurement target compounds and contaminant components can be removed by a two-stage mass filter, so that an ion intensity signal having a high S / N ratio can be obtained. Therefore, MRM measurement is particularly effective for quantifying trace components.

  Such a tandem quadrupole mass spectrometer may be used alone, but is often used in combination with a liquid chromatograph (LC) or a gas chromatograph (GC). For example, LC / MS / MS using a tandem quadrupole mass spectrometer as a liquid chromatograph detector is often used for quantitative analysis of compounds in samples containing many compounds or samples containing impurities.

  When performing MRM measurement in LC / MS / MS (or GC / MS / MS), prior to measurement of the target sample, the mass-to-charge ratio of the target precursor ion is correlated with the retention time of the target compound. Must be set as one of the measurement conditions. At this time, by setting the optimal combination of precursor ion and product ion mass-to-charge ratio for each target compound, the signal intensity of ions derived from each target compound can be obtained with high accuracy and sensitivity. The compound can be quantified with high accuracy and high sensitivity. The combination of the precursor ion and the product ion mass-to-charge ratio can be set manually by an analyst, but it takes a lot of time and effort, and the optimal combination cannot always be set. For this reason, as disclosed in Patent Document 1, an apparatus has been developed that can automatically set the optimum combination of precursor ion and product ion mass-to-charge ratio with high probability for a target compound.

  By the way, in order to determine the target compound with high accuracy and high sensitivity using MRM measurement, not only the optimum combination of the precursor ion and the product ion mass-to-charge ratio is set according to the target compound as described above. Therefore, it is necessary to set measurement conditions such as collision energy that is optimal for the combination. As described in Non-Patent Document 1, control parameters in MRM measurement (in the example of Non-Patent Document 1, the Q1 prerod voltage included in the front quadrupole mass filter and the Q3 prerod included in the rear quadrupole mass filter are described. A mass spectrometer equipped with a function for automatically optimizing voltage, collision energy CE, etc. (hereinafter, this function is referred to as “MRM measurement condition optimization function”) is also known.

The conventional MRM measurement condition optimization function has the following two methods.
(1) An analyst designates a set of mass-to-charge ratios of precursor ions and product ions derived from a target compound. Then, by executing an analysis on a known sample containing the compound (standard sample, etc.), the optimum control parameter value is searched for the specified precursor ion and product ion mass-to-charge ratio pair, and the result is displayed. Is done.
(2) The analyst specifies only the mass-to-charge ratio of the precursor ion derived from the target compound. Then, the product ion scan measurement for the designated precursor ion is performed on the known sample containing the compound, and a predetermined number of product ion peaks are selected in descending order of the signal intensity in the product ion spectrum obtained thereby. Then, optimum control parameter values are searched for the mass-to-charge ratio pair of the original precursor ion and each selected product ion, and the result is displayed.

  In the method (1), the analyst needs to know not only the precursor ion derived from the compound but also the mass-to-charge ratio of the product ion. On the other hand, the method (2) has an advantage that an appropriate product ion is automatically searched and a control parameter value can be obtained without knowing the mass-to-charge ratio of the product ion to be targeted by the analyst. is there. However, when multiple product ions are generated for a single precursor ion, the product ion that exhibits a large signal intensity is not necessarily the optimum ion for quantification, and the product ion with a lower signal intensity is the peak. In some cases, the purity is high and suitable for quantification. As described above, when the product ions that are optimal for quantification do not fall within the specified number in terms of intensity, the method (2) above cannot obtain the optimum parameter values for the ions.

  The conventional MRM measurement condition optimization function described above performs analysis by introducing a standard sample or a sample containing a single compound into an ion source of a tandem quadrupole mass spectrometer by infusion or flow injection. Is assumed. Therefore, the control parameter values for MRM measurement can be optimized only for the mass-to-charge ratio of one precursor ion by a series of measurements for one sample injection. Therefore, when there are a large number of precursor ions for which the control parameter value is to be optimized, it is necessary to repeat the sample injection and the series of measurements by that number, and it takes a considerable time to optimize the MRM measurement conditions.

JP 2013-15485 A

"LCMS-8040 ultra-high-speed triple quadrupole LC / MS / MS system MRM optimization function", Shimadzu Corporation, [October 3, 2013 search], Internet <URL: http://www.an .shimadzu.co.jp / lcms / lcms8040 / 8040-5.htm # 1>

  The present invention has been made to solve the above-mentioned problems, and its main object is to reduce the signal intensity of product ions to be targeted when optimizing the control parameter values for MRM measurement. Even in such a case, it is an object to provide a tandem quadrupole mass spectrometer capable of reliably optimizing MRM measurement conditions for, for example, product ions suitable for quantification for each target compound.

  Another object of the present invention is to shorten the time required for optimizing MRM measurement conditions for ions derived from a large number of compounds in a tandem quadrupole mass spectrometer having a liquid chromatograph or gas chromatograph connected to the preceding stage. It is an object to provide a tandem quadrupole mass spectrometer that can be used.

A first aspect of the present invention made to solve the above-described problem is a tandem quadrupole mass spectrometer having a quadrupole mass filter before and after a collision cell for cleaving ions, In a tandem quadrupole mass spectrometer that performs MRM measurement condition optimization that searches for optimum MRM measurement conditions for one or more compounds while performing multiple reaction monitoring (MRM) measurement for
a) As a measurement condition for optimizing the MRM measurement condition, a priority ion registration unit that registers a mass-to-charge ratio of one or more product ions to be preferentially targeted for each precursor ion;
b) When performing MRM measurement condition optimization targeting a precursor ion derived from one compound, information on a priority product ion corresponding to the precursor ion is obtained from the priority ion registration unit, and When the priority product ion is detected as a product ion, the MRM measurement conditions are optimized for the combination of the precursor ion and the mass-to-charge ratio of the priority product ion, and each part is controlled so as to obtain an optimal control parameter. An MRM measurement condition optimization executing unit,
It is characterized by having.

  In the tandem quadrupole mass spectrometer according to the first aspect of the present invention, before performing the operation of optimizing the MRM measurement conditions, the analyst can calculate the mass charge of the precursor ion targeted for one or more target compounds. A ratio is designated, and a mass-to-charge ratio of one or more product ions to be preferentially targeted is designated for each precursor ion, that is, for each target compound. The designated product ion is registered for each precursor ion by the priority ion registration unit.

  When the MRM measurement condition optimization is executed while actually measuring a known sample containing the target compound, the MRM measurement condition optimization execution unit selects the quadrupole mass in the previous stage so that the precursor ion designated for the target compound is selected. While controlling the filter, the latter-stage quadrupole mass filter is controlled so that scan measurement (product ion scan measurement) in a predetermined mass-to-charge ratio range is performed. Thereby, since a product ion spectrum in a predetermined mass-to-charge ratio range is obtained, a peak corresponding to the product ion is detected in the spectrum. Then, when the detected product ion is registered in the preferential ion registration unit as a preferential product ion for the precursor ion, the product ion is extracted as a target. Subsequently, for the combination of the precursor ion and the product ion mass-to-charge ratio, for example, the optimum value of the collision energy is obtained by examining the change in the product ion intensity when the collision energy is changed.

  According to the tandem quadrupole mass spectrometer of the first aspect, for example, even a product ion having a smaller signal intensity than other product ions can be reliably registered by registering it in the preferred ion registration unit. In addition, MRM measurement conditions can be optimized. Thereby, MRM measurement condition optimization can be performed on a combination of the mass-to-charge ratio of a precursor ion and a product ion intended by an analyst, and an optimal control parameter can be obtained for a certain compound. On the other hand, since MRM measurement condition optimization is not performed for product ions that are unnecessary even if the signal intensity is large or are not significant in analysis, it is possible to avoid wasting time in optimizing MRM measurement conditions.

  In the tandem quadrupole mass spectrometer of the first aspect, in principle, even when a certain product ion is detected for a certain precursor ion, the product ion is registered in the preferred ion registration unit. Otherwise, the MRM measurement condition is not optimized. However, there is a time margin after performing MRM measurement optimization for the product ions registered in the preferred ion registration unit, or there are ions that correspond to the product ions registered in the preferred ion registration unit. If not, product ions that are not registered in the priority ion registration unit may be targeted for MRM measurement condition optimization.

  In addition, a second aspect of the present invention made to solve the above problem is a tandem quadrupole mass spectrometer having a quadrupole mass filter before and after sandwiching a collision cell for cleaving ions, In a tandem quadrupole mass spectrometer that performs MRM measurement condition optimization that searches for optimum MRM measurement conditions for one or more compounds while performing multiple reaction monitoring (MRM) measurement on a sample.
  a) As a measurement condition for optimizing the MRM measurement condition,Exclude as targetRegister the mass-to-charge ratio of one or more product ions for each precursor ionExclusionAn ion registration department;
  b) When performing MRM measurement condition optimization targeting a precursor ion derived from one compound, information on the excluded product ion corresponding to the precursor ion ExclusionOptimizing MRM measurement conditions for a combination of mass-to-charge ratios of the precursor ions and the remaining excluded product ions by removing at least the excluded product ions from the ions acquired from the ion registration unit and detected as product ions for the precursor ions Performing an MRM measurement condition optimization executing unit for controlling each unit so as to obtain an optimal control parameter;
It is characterized by having.

  In the tandem quadrupole mass spectrometer according to the second aspect of the present invention, before performing the operation of optimizing the MRM measurement conditions, the analyst can calculate the mass charge of the precursor ion targeted for one or more target compounds. A ratio is designated, and the mass-to-charge ratio of one or a plurality of product ions to be excluded as targets is designated for each precursor ion, that is, for each target compound. The designated product ion is registered for each precursor ion by the exclusion ion registration unit.

  When the MRM measurement condition optimization is executed while actually measuring a known sample containing the target compound, the MRM measurement condition optimization execution unit selects the quadrupole mass in the previous stage so that the precursor ion designated for the target compound is selected. While controlling the filter, the latter-stage quadrupole mass filter is controlled so that scan measurement (product ion scan measurement) in a predetermined mass-to-charge ratio range is performed. Thereby, since a product ion spectrum in a predetermined mass-to-charge ratio range is obtained, a peak corresponding to the product ion is detected in the spectrum. Then, the product ions registered in the excluded ion registration unit are excluded from the detected product ions, and for the remaining product ions, for example, a predetermined number of product ions are extracted in descending order of the signal intensity. Subsequently, for the combination of the precursor ion and the product ion mass-to-charge ratio, for example, the optimum value of the collision energy is obtained by examining the change in the product ion intensity when the collision energy is changed.

According to the second tandem quadrupole mass spectrometer aspects, even product ion signal intensity is greater For example, by registering the exclusion ion registration section, reliably MRM measurement conditions optimum can it to exclude from the reduction of the target. Thereby, signal strength is greater by a required or analytically, since MRM measurement conditions optimized for product ions not significant is not performed, it is possible to avoid waste time MRM measurement condition optimization it can.

  Of course, the first embodiment and the second embodiment can be combined. For example, after excluding the product ions registered in the exclusion ion registration unit from the product ions detected in the product ion spectrum, the priority ion registration is not performed in the order of the signal intensity among the remaining product ions. It is preferable to extract the product ions registered in the unit as a target preferentially, and to optimize the MRM measurement conditions for the combination of the precursor ion and the product ion mass-to-charge ratio.

Further, the third aspect of the present invention, which has been made to solve the above problems, is that a chromatograph that temporally separates the compounds in the sample is connected to the preceding stage to ionize the compounds in the introduced sample. An ion source, a pre-quadrupole mass filter for selecting ions having a specific mass-to-charge ratio among the various ions generated by the ion source as precursor ions, a collision cell for dissociating the precursor ions, and a dissociation cell generated by the dissociation A multi-reaction monitoring system comprising: a post-stage quadrupole mass filter that selects ions having a specific mass-to-charge ratio among various product ions; and a detector that detects ions that have passed through the post-stage quadrupole mass filter. (MRM) A table for optimizing MRM measurement conditions for searching for optimum MRM measurement conditions for one or a plurality of compounds while performing measurement. In dem quadrupole mass spectrometer,
a) As a measurement condition for optimizing MRM measurement conditions, for each target compound, a measurement condition setting unit that presets a mass-to-charge ratio of a target precursor ion, a measurement start time, and a measurement end time; ,
b) When optimizing the MRM measurement conditions, based on the information on the measurement start time and the measurement end time set in the measurement condition setting unit, target compounds that can be measured sequentially as time passes so that the measurement times do not overlap. Select and execute MRM measurement condition optimization for each target compound as a series of measurements by one chromatographic analysis, and perform MRM measurement condition optimization for all target compounds with a minimum number of chromatographic analyzes A measurement sequence creation unit for creating a measurement sequence for optimizing MRM measurement conditions;
c) an MRM measurement condition optimization execution unit that executes MRM measurement condition optimization while controlling each unit in accordance with the measurement sequence created by the measurement sequence creation unit;
It is characterized by having.

  In a liquid chromatograph mass spectrometer, a sample containing a single compound is generally introduced into a tandem quadrupole mass spectrometer by infusion or flow injection to optimize MRM measurement conditions for the compound. In the tandem quadrupole mass spectrometer according to the third aspect of the present invention, a sample containing a plurality of target compounds is introduced into a chromatograph, and the target compounds are separated temporally, and the separated compounds are included. The eluate is introduced into a mass spectrometer and MRM measurement conditions for each target compound are optimized. However, when the retention times of a plurality of target compounds are close, it is difficult to perform MRM measurement condition optimization for the plurality of target compounds in the same time zone.

  Therefore, in the tandem quadrupole mass spectrometer according to the third aspect, the analyzer performs measurement for optimizing the MRM measurement conditions by the measurement condition setting unit before performing the work for optimizing the MRM measurement conditions. As conditions, a mass-to-charge ratio of a target precursor ion, a measurement start time, and a measurement end time are preset for each target compound. The measurement start time and measurement end time may be appropriately determined based on the known retention time of each compound. When such measurement conditions are set, the measurement sequence creation unit 1 or 2 for executing MRM measurement condition optimization for all target compounds based on the set measurement start time and measurement end time information. Create a measurement sequence for multiple chromatographic mass spectrometry.

  In other words, the target compounds that can be measured sequentially over time so that the measurement times do not overlap are selected and used as a series of measurements by one chromatographic mass spectrometry. Compounds that cannot be optimized for MRM measurement conditions by mass spectrometry are sent to the second chromatographic mass analysis. Of course, if there remains a compound that cannot be subjected to MRM measurement condition optimization even by two chromatographic mass spectrometry measurements, the third and subsequent chromatographic mass spectrometry may be performed. After the measurement sequence is created in this way, the MRM measurement condition optimization execution unit executes MRM measurement condition optimization while controlling each unit according to the measurement sequence. Thereby, MRM measurement condition optimization for all target compounds can be achieved by a minimum number of chromatographic mass spectrometry.

  Of course, the control and processing of the tandem quadrupole mass spectrometer according to the first aspect or the second aspect can be combined with the tandem quadrupole mass spectrometer according to the third aspect.

  According to the tandem quadrupole mass spectrometer of the first and second aspects of the present invention, the signal intensity of the product ion to be targeted for the target compound is higher than that of other product ions when optimizing the MRM measurement conditions. Even in such a case, it is possible to prevent omission of searching for an optimal control parameter value for such product ions. On the other hand, it is possible to avoid performing optimization of MRM measurement conditions for unnecessary or undesired product ions, so that wasteful time is not spent for such work and MRM measurement conditions can be optimized efficiently. .

  According to the tandem quadrupole mass spectrometer of the third aspect of the present invention, optimization of MRM measurement conditions for a combination of mass-to-charge ratios of precursor ions and product ions derived from a large number of target compounds can be performed in a short time. Can be done efficiently.

The block diagram of the principal part of the liquid chromatograph mass spectrometer which used the tandem quadrupole-type mass spectrometer by one Example of this invention. The flowchart of the process at the time of optimizing MRM measurement conditions in the liquid chromatograph mass spectrometer of a present Example. The figure which shows an example of the MRM measurement condition setting screen used when performing MRM measurement condition optimization in the liquid chromatograph mass spectrometer of a present Example. The figure which shows an example of the product ion selection condition setting screen used when performing MRM measurement condition optimization in the liquid chromatograph mass spectrometer of a present Example.

  Hereinafter, an embodiment of a liquid chromatograph mass spectrometer using a tandem quadrupole mass spectrometer according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a configuration diagram of a main part of the liquid chromatograph mass spectrometer of the present embodiment.

  In the liquid chromatograph mass spectrometer of the present embodiment, the liquid chromatograph unit 1 includes a mobile phase container 10 in which a mobile phase is stored, a pump 11 that sucks the mobile phase and delivers it at a constant flow rate, and a mobile phase. And a column 13 for separating various compounds contained in the sample in the time direction. The pump 11 sucks the mobile phase from the mobile phase container 10 and sends it to the column 13 at a constant flow rate. When a certain amount of sample liquid is introduced into the mobile phase from the injector 12, the sample is introduced into the column 13 along the flow of the mobile phase, and various compounds in the sample are separated in the time direction while passing through the column 13. Then, it elutes from the outlet of the column 13 and is introduced into the mass spectrometer 2.

  The mass spectrometer 2 includes a first vacuum whose degree of vacuum is increased stepwise between an ionization chamber 20 that is substantially atmospheric pressure and a high-vacuum analysis chamber 23 that is evacuated by a high-performance vacuum pump (not shown). This is a configuration of a multistage differential exhaust system including second intermediate vacuum chambers 21 and 22. The ionization chamber 20 is provided with an electrospray ionization probe 201 for spraying while applying a charge to the sample solution, and a thin heating capillary 202 is passed between the ionization chamber 20 and the first intermediate vacuum chamber 21 at the next stage. Communicate. The first intermediate vacuum chamber 21 and the second intermediate vacuum chamber 22 are separated by a skimmer 212 having a small hole at the top, and ions are focused in the first intermediate vacuum chamber 21 and the second intermediate vacuum chamber 22, respectively. However, ion guides 211 and 221 for transporting to the subsequent stage are installed. The analysis chamber 23 sandwiches a collision cell 232 in which a multipole ion guide 233 is installed, and a front quadrupole mass filter 231 that separates ions according to a mass-to-charge ratio. A post-stage quadrupole mass filter 234 and an ion detector 235 are separated.

  In the MS / MS analysis, CID gas such as argon or nitrogen is continuously or intermittently supplied into the collision cell 232. The power supply unit 24 applies predetermined voltages to the electrospray ionization probe 201, the ion guides 211, 221, 233, the quadrupole mass filters 231, 234, and the like. Each of the quadrupole mass filters 231 and 234 has a pre-rod electrode for correcting the disturbance of the electric field at the inlet end in front of the main rod electrode. The pre-rod electrode is different from the main rod electrode. A voltage can be applied.

  In the mass spectrometer 2, when the eluate from the column 13 reaches the electrospray ionization probe 201, the eluate is sprayed while being charged at the tip of the probe 201. The charged droplets formed by spraying are finely divided while being disrupted by the action of electrostatic force due to the applied charge, and in the process, the solvent is vaporized and ions derived from the compound are ejected. The ions thus generated are sent to the first intermediate vacuum chamber 21 through the heating capillary 202, converged by the ion guide 211, and sent to the second intermediate vacuum chamber 22 through a small hole at the top of the skimmer 212. The ions derived from the compound are converged by the ion guide 221, sent to the analysis chamber 23, and introduced into the space in the long axis direction of the front quadrupole mass filter 231. Note that the ionization method is not limited to the electrospray ionization method, and an atmospheric pressure chemical ionization method, an atmospheric pressure photoionization method, or the like may be used.

  When performing MS / MS analysis in the mass spectrometer 2, a predetermined voltage (high-frequency voltage and DC voltage) is applied to each rod electrode of the front-stage quadrupole mass filter 231 and the rear-stage quadrupole mass filter 234 from the power supply unit 24. Is applied), and CID gas is supplied into the collision cell 232 continuously or intermittently. Of the various ions sent to the front quadrupole mass filter 231, only ions having a specific mass-to-charge ratio corresponding to the voltage applied to each rod electrode of the front quadrupole mass filter 231 are included in the filter 231. And is introduced into the collision cell 232 as a precursor ion. In the collision cell 232, the precursor ions collide with the CID gas and dissociate, and various product ions are generated. When the generated various product ions are introduced into the post-stage quadrupole mass filter 234, only product ions having a specific mass-to-charge ratio corresponding to the voltage applied to each rod electrode of the post-stage quadrupole mass filter 234 Passes through the filter 234, reaches the ion detector 235, and is detected. The ion detector 235 is, for example, a pulse count type detector, and outputs a number of pulse signals corresponding to the number of incident ions to the data processing unit 4 as detection signals.

The data processing unit 4 includes a product ion automatic selection unit 41 as a functional block. The control unit 5 to which the input unit 6 and the display unit 7 are connected includes a pump 11 and an injector 12 of the liquid chromatograph unit 1, a power supply unit 24 of the mass spectrometer 2 and a CID gas supply unit (not shown). Control each action. The control unit 5 includes, as functional blocks, a normal measurement execution control unit 51, a measurement condition optimization control unit 52, an optimal parameter storage unit 57, and the like. The measurement condition optimization control unit 52 includes an optimization measurement condition setting unit 53 and a priority. / Excluded ion information storage unit 54, measurement sequence creation unit 55, optimization measurement execution unit 56, etc. The normal measurement execution control unit 51 controls each unit when performing chromatographic mass spectrometry on the target sample in order to identify (qualitatively) and quantify the compound in the target sample. On the other hand, the measurement condition optimization control unit 52 controls each unit when performing preliminary measurement for optimizing the control parameter for controlling each unit when performing various measurements such as MRM measurement condition optimization described later. To do. The optimum parameter storage unit 57 stores the control parameter value obtained under the control of the measurement condition optimization control unit 52 for the measurement performed under the control of the normal measurement execution control unit 51. It is something to keep.
Note that at least some of the functions of the control unit 5 and the data processing unit 4 are realized by using a personal computer as hardware resources and executing dedicated control / processing software installed in the computer in advance on the computer. be able to.

  The liquid chromatograph mass spectrometer of this embodiment is characterized by control and processing for optimizing MRM measurement conditions for optimizing measurement conditions for MRM measurement. Hereinafter, this point will be described with reference to FIGS. FIG. 2 is a flowchart of processing when optimizing MRM measurement conditions in the liquid chromatograph mass spectrometer of the present embodiment, and FIGS. 3 and 4 are MRM measurement condition setting screens and products used when optimizing MRM measurement conditions. It is a figure which shows an example of an ion selection condition setting screen.

  Prior to optimizing the MRM measurement conditions, the analyst inputs and sets the measurement time range and the target precursor ion mass-to-charge ratio from the input unit 6 for each target compound to be optimized (step S1). . The target compound in this case is a compound to be quantified contained in the target sample.

Specifically, when the analyst performs a predetermined operation on the input unit 6, the optimization measurement condition setting unit 53 in the control unit 5 displays an MRM measurement condition setting screen 100 as shown in FIG. 3 on the screen of the display unit 7. To display. When optimizing the applied voltage and collision energy of each part as the MRM measurement condition, this is done by putting a check mark in the “voltage optimization” check box 101a in the item setting part 101 in the MRM measurement condition setting screen 100. Select. Also, instead of directly inputting the mass-to-charge ratio of the target product ions for each compound, when performing an automatic search for product ions , a check mark can be placed in the “product ion automatic selection” check box 101b. Select this. Then, in the measurement target compound table 102, the compound name of the target compound, the mass-to-charge ratio of the target precursor ion (“precursor m / z”), the polarity of the precursor ion (“+/−”), measurement Enter the start time (“Start (min)”), measurement end time (“End (min)”), etc. The measurement start time and measurement end time may be determined with reference to the known retention time of the target compound, with an appropriate time margin before and after (± 0.5 min in this example).

  In this example, when “voltage optimization” is selected, optimization of the pre-rod electrode voltage of the pre-quadrupole mass filter 231, the pre-rod electrode voltage of the post-quadrupole mass filter 234, collision energy, etc. is selectively performed. Can be done. More detailed conditions such as selection of the optimization target region and voltage range can be set on a newly opened screen by clicking the “advanced setting” button.

When “automatic product ion selection” is selected, priority ions and exclusion ions can be set for the product ions targeted for each precursor ion. That is, when an analyst clicks on the input unit 6 on an arbitrary row in the measurement target compound table 102 of the MRM measurement condition setting screen 100, that is, a row in which the mass-to-charge ratio of a desired precursor ion is set, The measurement measurement condition setting unit 53 displays a product ion selection condition setting screen 200 as shown in FIG. 4 on the screen of the display unit 7 for the designated product ions. On the product ion selection condition setting screen 200, a precursor ion information display unit 205 to be set, an excluded ion list 206, and a priority ion list 203 are arranged.

The analyst sets the mass-to-charge ratio of ions to be excluded as product ions when optimizing the MRM measurement conditions and the mass-to-charge ratio of ions to be preferentially optimized for MRM measurement conditions, respectively, as the excluded ion list 206 and the priority ions. Input to the list 203. For example, when there is a possibility that a known contaminant is mixed in the mobile phase of the liquid chromatograph, register the product ion derived from the contaminant as an excluded ion, or derive from another component with a short retention time The product ions may be registered as excluded ions. In addition, when product ions generated from precursor ions derived from the target compound are known to some extent, these product ions may be registered as preferred ions. When the input of the excluded ions or the priority ions is completed, the input is confirmed by clicking the “OK” button 204. Information on the confirmed priority ions and exclusion ions is stored in the priority / exclusion ion information storage unit 54. By performing the above operation for each precursor ion described in the measurement target compound table 102, different preferential ions and excluded ions can be specified for all the precursor ions.

  Then, when the analyst clicks the “execute” button 103 on the MRM measurement condition setting screen 100, the measurement sequence creation unit 55 performs MRM measurement based on the information described in the measurement target compound table 102 at that time. A measurement sequence for performing optimization is created (step S3). That is, the measurement sequence creation unit 55 collects measurement start time and measurement end time information for all the compounds registered in the measurement target compound table 102, and obtains a measurement time range of each compound. Then, compounds are selected in order of increasing time under the condition that the measurement time ranges do not overlap. For example, in the example of FIG. 3, the measurement time range of compound b (2.346-3.346 min) overlaps with the measurement time range of compound h (2.682-3.682 min) and the measurement time range of compound e (3.013-4.013 min). Therefore, if the compound a and the compound b are selected in order, it is the compound d whose measurement time range is 3.425-4.425 min that can be selected next in ascending order of time. That is, here, the compound h and the compound e are not selected. Thus, the compounds are selected while confirming the overlap of the measurement time ranges in order until the compound having the slowest measurement time range. Then, the measurement sequence is determined so as to sequentially measure the first selected compound. Next, compounds that are not selected in the first time are selected in order of increasing time under the condition that the measurement time ranges do not overlap. Then, the compounds are selected while confirming the overlap of the measurement time ranges in order until the compound having the slowest measurement time range, and the measurement sequence is determined so that the compounds selected for the second time are measured in order. By repeating this until all the compounds are selected, n measurement sequences are determined. n may be 1, and the value of n increases as the number of compounds having similar retention times increases.

  When the measurement sequences for all the target compounds are determined as described above, the optimization measurement execution unit 56 performs the chromatographic mass analysis on the prepared sample according to the measurement sequences and optimizes the MRM measurement conditions. (Steps S4 and S5). The sample used at this time is a known sample containing the compound (the compound part a, b, h,... In the example of FIG. 3) previously set by the analyst in step S1.

  With the start of measurement, the sample is injected from the injector 12 into the mobile phase fed by the pump 11 in the liquid chromatograph unit 1. While the sample passes through the column 13, the compounds in the sample are separated in the time direction and introduced into the mass spectrometer 2 in order. The mass spectrometer 2 optimizes the MRM measurement conditions for the precursor ion derived from the compound associated with the measurement time range for each measurement time range determined in the measurement sequence. In the processing unit 4, the product ion automatic selection unit 41 determines a target product ion for which MRM measurement condition optimization is performed.

  That is, first, a product ion scan measurement over a predetermined mass-to-charge ratio range is performed on a precursor ion derived from a target compound. The product ion automatic selection unit 41 creates a product ion spectrum based on the detection signal obtained by the ion detector 235 at this time. Then, among the peaks appearing in the product ion spectrum, for example, a peak whose peak intensity is a predetermined threshold or more is extracted, and a mass-to-charge ratio corresponding to each extracted peak is obtained. The mass-to-charge ratio obtained here is the mass-to-charge ratio of the product ion candidate. Subsequently, information on preferred ions and excluded ions registered for the precursor ion derived from the target compound is obtained from the preferred / excluded ion information storage unit 54. Are searched for whether they are designated as excluded ions, and if they are applicable, they are excluded from the product ion candidates. On the other hand, when a preferential ion is designated, a search is made as to whether any of the product ion candidates is designated as a preferential ion, and if there is a relevant ion, it is determined as a product ion. In the case where no preferential ions are designated, for example, the number of ions designated in order of peak intensity from among the product ion candidates may be determined as product ions. If the number of preferential ions is specified but the number is small, select a preferential ion and then add an appropriate number of ions as product ions in the order of peak intensity from the remaining product ion candidates. You may make it to decide.

  In this way, the product ion automatic selection unit 41 determines one or a predetermined number of product ions for performing MRM measurement condition optimization for one target compound. The determined product ion information is sent to the optimization measurement execution unit 56, and the optimization measurement execution unit 56 executes optimization of MRM measurement conditions for the mass-to-charge ratio pair of the precursor ion derived from the target compound and the product ion. To do. For example, while sequentially changing the collision energy to a predetermined value in multiple steps, the ion signal intensity is measured for a predetermined set of precursor ion and product ion mass-to-charge ratio, and the value of the collision energy that maximizes the signal intensity Find out. Similarly, the optimum value is searched for the voltage applied to the pre-rod electrode of each quadrupole mass filter 231, 234. When multiple product ions are defined for a precursor ion derived from a single compound, optimum values of collision energy and applied voltage are searched for each set of mass-to-charge ratios of the precursor ion and product ion. . Since these series of processes are performed within the measurement time range defined in the measurement sequence, for each measurement time range, a plurality of sets of mass-to-charge ratios of precursor ions and product ions for a certain compound are obtained. The optimum value of the control parameter is obtained. The optimal control parameter value obtained here is stored in the optimal parameter storage unit 57.

  When a series of measurements for one sample injection is completed (step S6), it is determined whether optimization of MRM measurement conditions for all designated compounds is completed (step S7). If there is a compound for which MRM measurement condition optimization has not been completed, that is, if there is an unexecuted measurement sequence, the process returns to step S5, and the same sample is injected according to the measurement sequence, and the second liquid chromatograph mass is obtained. The analysis is performed and MRM measurement condition optimization is performed for the remaining compounds. When the optimization of MRM measurement conditions for all target compounds is finally completed, the measurement and processing are ended.

  Through the above measurement and processing, an optimal control parameter value for MRM measurement is obtained for each set of mass-to-charge ratios of the precursor ion derived from the target compound and the product ion, and is stored in the optimal parameter storage unit 57. Subsequently, when the MRM measurement is performed to quantify the target compound contained in the unknown sample, the normal measurement execution control unit 51 uses the control parameter optimum value stored in the optimum parameter storage unit 57, and uses the mass spectrometer. 2 parts are controlled. Thereby, MRM measurement results can be obtained under conditions optimal for quantification, and high quantification accuracy and sensitivity can be realized.

  Since the above embodiment is an example of the present invention, it is obvious that any modification, addition, or modification as appropriate within the scope of the present invention is included in the scope of the claims of the present application.

DESCRIPTION OF SYMBOLS 1 ... Liquid chromatograph part 10 ... Mobile phase container 11 ... Pump 12 ... Injector 13 ... Column 2 ... Mass spectrometer 20 ... Ionization chamber 201 ... Electrospray ionization probe 202 ... Heating capillary 21, 22 ... Intermediate vacuum chamber 211, 221 ... ion guide 212 ... skimmer 23 ... analysis chamber 231 ... front-stage quadrupole mass filter 232 ... collision cell 233 ... multipole ion guide 234 ... back-stage quadrupole mass filter 235 ... ion detector 24 ... power supply section 4 ... data processing section 41 ... Automatic product ion selection unit 5 ... Control unit 51 ... Normal measurement execution control unit 52 ... Measurement condition optimization control unit 53 ... Optimization measurement condition setting unit 54 ... Priority / exclusion ion information storage unit 55 ... Measurement sequence creation unit 56 ... Optimization measurement execution part 57 ... Optimum parameter storage part 6 ... Input part 7 ... Display part

Claims (5)

A tandem quadrupole mass spectrometer having a quadrupole mass filter on both sides of a collision cell for cleaving ions, which is optimal for one or more compounds while performing multiple reaction monitoring (MRM) measurement on a sample In a tandem quadrupole mass spectrometer that performs MRM measurement condition optimization to search for MRM measurement conditions,
a) As a measurement condition for optimizing the MRM measurement condition, a priority ion registration unit that registers a mass-to-charge ratio of one or more product ions to be preferentially targeted for each precursor ion;
b) When performing MRM measurement condition optimization targeting a precursor ion derived from one compound, information on a priority product ion corresponding to the precursor ion is obtained from the priority ion registration unit, and When the priority product ion is detected as a product ion, the MRM measurement conditions are optimized for the combination of the precursor ion and the mass-to-charge ratio of the priority product ion, and each part is controlled so as to obtain an optimal control parameter. An MRM measurement condition optimization executing unit,
A tandem quadrupole mass spectrometer. A tandem quadrupole mass spectrometer having a quadrupole mass filter on both sides of a collision cell for cleaving ions, which is optimal for one or more compounds while performing multiple reaction monitoring (MRM) measurement on a sample In a tandem quadrupole mass spectrometer that performs MRM measurement condition optimization to search for MRM measurement conditions,
a) Exclusion ion registration unit for registering, for each precursor ion, the mass-to-charge ratio of one or more product ions to be excluded as targets as measurement conditions for optimizing MRM measurement conditions;
b) When performing MRM measurement condition optimization targeting a precursor ion derived from one compound, information on an excluded product ion corresponding to the precursor ion is obtained from the excluded ion registration unit, and Exclude at least the excluded product ions from the ions detected as product ions, and optimize the MRM measurement conditions for the combination of the precursor ions and the mass-to-charge ratios of the remaining excluded product ions to obtain optimal control parameters. An MRM measurement condition optimization execution unit that controls each unit;
A tandem quadrupole mass spectrometer. A chromatograph that temporally separates the compounds in the sample is connected to the previous stage, and the ion source that ionizes the compounds in the introduced sample and the specific mass-to-charge ratio among the various ions generated by the ion source. A pre-quadrupole mass filter that sorts ions having precursor ions as a precursor ion, a collision cell that dissociates the precursor ions, and a quadruple stage that sorts ions having a specific mass-to-charge ratio among various product ions generated by the dissociation. A polar mass filter and a detector for detecting ions that have passed through the subsequent quadrupole mass filter are provided, and an optimum MRM measurement condition for one or a plurality of compounds is searched for while performing multiple reaction monitoring (MRM) measurement. In a tandem quadrupole mass spectrometer that optimizes MRM measurement conditions,
a) As a measurement condition for optimizing MRM measurement conditions, for each target compound, a measurement condition setting unit that presets a mass-to-charge ratio of a target precursor ion, a measurement start time, and a measurement end time; ,
b) When optimizing the MRM measurement conditions, based on the information on the measurement start time and the measurement end time set in the measurement condition setting unit, target compounds that can be measured sequentially as time passes so that the measurement times do not overlap. Select and execute MRM measurement condition optimization for each target compound as a series of measurements by one chromatographic analysis, and perform MRM measurement condition optimization for all target compounds with a minimum number of chromatographic analyzes A measurement sequence creation unit for creating a measurement sequence for optimizing MRM measurement conditions;
c) an MRM measurement condition optimization execution unit that executes MRM measurement condition optimization while controlling each unit in accordance with the measurement sequence created by the measurement sequence creation unit;
A tandem quadrupole mass spectrometer. The tandem quadrupole mass spectrometer according to claim 1,
The MRM measurement condition optimization execution unit determines whether or not there is a priority product ion in a product ion spectrum obtained by performing a product ion scan measurement for a precursor ion associated with a target compound, and the priority product A tandem quadrupole mass spectrometer characterized in that, when it is determined that there is an ion, the priority product ion is determined as an object for optimization of MRM measurement conditions. A tandem quadrupole mass spectrometer according to claim 2,
The MRM measurement condition optimization execution unit determines whether or not there is the excluded product ion in a product ion spectrum obtained by performing a product ion scan measurement for a precursor ion associated with a target compound, and the excluded product ion A tandem quadrupole mass spectrometer characterized in that, when it is determined that there is an ion, the excluded product ion is excluded from the target of MRM measurement condition optimization.

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